package cn.initcap.algorithm.swing.maze.dfs;

import cn.initcap.algorithm.swing.AlgoVisHelper;
import cn.initcap.algorithm.swing.BaseAlgoFrame;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;

/**
 * @author initcap
 * @date 8/1/19 10:46 AM
 */
public class AlgoVisualizer {

    private static final int[][] D = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}};
    private static int DELAY = 5;
    private static int blockSide = 8;
    private MazeData data;
    private BaseAlgoFrame frame;

    public AlgoVisualizer(String mazeFile) {

        // 初始化数据
        data = new MazeData(mazeFile);
        int sceneHeight = data.N() * blockSide;
        int sceneWidth = data.M() * blockSide;

        // 初始化视图
        EventQueue.invokeLater(() -> {
            frame = new BaseAlgoFrame("Maze Solver Visualization", sceneWidth, sceneHeight) {
                @Override
                public void draw(Graphics graphics) {
                    Graphics2D g2d = (Graphics2D) graphics;
                    int w = sceneWidth / data.M();
                    int h = sceneHeight / data.N();

                    for (int i = 0; i < data.N(); i++) {
                        for (int j = 0; j < data.M(); j++) {
                            if (data.getMaze(i, j) == MazeData.WALL) {
                                AlgoVisHelper.setColor(g2d, AlgoVisHelper.LIGHT_BLUE);
                            } else {
                                AlgoVisHelper.setColor(g2d, AlgoVisHelper.WHITE);
                            }

                            if (data.path[i][j]) {
                                AlgoVisHelper.setColor(g2d, AlgoVisHelper.YELLOW);
                            }

                            AlgoVisHelper.fillRectangle(g2d, j * w, i * h, w, h);
                        }
                    }
                }
            };

            new Thread(() -> {
                run();
            }).start();
        });
    }

    public static void main(String[] args) {

        String mazeFile = "algorithm/maze_101_101.txt";

        new AlgoVisualizer(mazeFile);
    }

    public void run() {

        setData(-1, -1, false);

        if (!go(data.getEntranceX(), data.getEntranceY())) {
            System.out.println("The maze has NO solution!");
        }

        setData(-1, -1, false);
    }

    /**
     * 从(x,y)的位置开始求解迷宫，如果求解成功，返回true；否则返回false
     *
     * @param x
     * @param y
     * @return
     */
    private boolean go(int x, int y) {

        if (!data.inArea(x, y)) {
            throw new IllegalArgumentException("x,y are out of index in go function!");
        }

        data.visited[x][y] = true;
        setData(x, y, true);

        if (x == data.getExitX() && y == data.getExitY()) {
            return true;
        }

        for (int i = 0; i < 4; i++) {
            int newX = x + D[i][0];
            int newY = y + D[i][1];
            if (data.inArea(newX, newY) &&
                    data.getMaze(newX, newY) == MazeData.ROAD &&
                    !data.visited[newX][newY]) {
                if (go(newX, newY)) {
                    return true;
                }
            }
        }

        // 回溯
        setData(x, y, false);

        return false;
    }

    private void setData(int x, int y, boolean isPath) {
        if (data.inArea(x, y)) {
            data.path[x][y] = isPath;
        }

        frame.render(data);
        AlgoVisHelper.pause(DELAY);
    }
}